/Engine/Source/Runtime/Engine/Classes/Animation/AnimNode_CustomProperty.h
We only subscribe to the OnInitializeAnimInstance path because we need to cache our source object, so we only override these methods in editor at the moment
virtual void OnInitializeAnimInstance ( const [FAnimInstanceProxy](API\Runtime\Engine\Animation\FAnimInstanceProxy) * InProxy, const [UAnimInstance](API\Runtime\Engine\Animation\UAnimInstance) * InAnimInstance )